Conservation of Endemic Bartram's Bass: Nesting Microhabitat Use and Spatial Distribution with Congeners in the Savannah River Basin
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Clemson University TigerPrints All Theses Theses 12-2018 Conservation of Endemic Bartram's Bass: Nesting Microhabitat Use and Spatial Distribution with Congeners in the Savannah River Basin Emily Elizabeth Judson Clemson University, [email protected] Follow this and additional works at: https://tigerprints.clemson.edu/all_theses Recommended Citation Judson, Emily Elizabeth, "Conservation of Endemic Bartram's Bass: Nesting Microhabitat Use and Spatial Distribution with Congeners in the Savannah River Basin" (2018). All Theses. 3255. https://tigerprints.clemson.edu/all_theses/3255 This Thesis is brought to you for free and open access by the Theses at TigerPrints. It has been accepted for inclusion in All Theses by an authorized administrator of TigerPrints. For more information, please contact [email protected]. CONSERVATION OF ENDEMIC BARTRAM'S BASS: NESTING MICROHABITAT USE AND SPATIAL DISTRIBUTION WITH CONGENERS IN THE SAVANNAH RIVER BASIN A Thesis Presented to the Graduate School of Clemson University In Partial Fulfillment of the Requirements for the Degree Master of Science Wildlife and Fisheries Biology by Emily Elizabeth Judson December 2018 Accepted by: Dr. Brandon Peoples, Committee Chair Dr. Troy Farmer Mrs. Jean Leitner ABSTRACT Bartram’s Bass Micropterus sp. cf cataractae is endemic to the Savannah River basin of South Carolina and Georgia. Bartram’s Bass is threatened by habitat alteration and hybridization with invasive Alabama bass (M. henshalli) and other non-native co- occurring congeners. This study aimed to identify reproductive habitat preference of this species, and factors contributing to its occurrence. In Chapter 1 we identified Bartram’s Bass nesting preference throughout the upper portion of its native range. In spring/summer 2017 and 2018, snorkel surveys were performed in tributaries to quantify nesting microhabitat use of Bartram’s Bass. Zig-zag transects were used to locate nests and to quantify habitat availability. Nesting microhabitat parameters were recorded at each nest detected, and eggs were collected for genetic analysis. Average velocity at the 39 pure Bartram’s Bass nests observed was 0.09 ± 0.02 m/s, SD, lower than average available velocity of 0.22 ± 0.01 m/s, SD (p= 0.0028). Average depth of nests was 0.70 ± 0.04 m, SD and was similar to those available 0.67 ± 0.02 m, SD (p= 0.6946). The substrates used in nests during both breeding years combined were primarily silt (36%), cobble (31%), and gravel (21%), whereas the most available substrates observed in transects were bedrock (23%) and cobble (23%) (P<0.0001). On average, nests were 1.84 ± 0.25 m from the nearest bank, and 4.67 ± 0.56 m from the nearest upstream flow influence. Differences between available and used habitat metrics indicate that velocity may be more important than depth or substrate when Bartram’s bass are selecting nest sites. While there is a relationship between substrate use and availability, we believe the main factor driving ii substrate use is velocity and that certain substrate types are likely a byproduct of selection for velocity. In Chapter 2 we determined the relative importance of abiotic factors and distance from reservoirs for predicting occurrence of Bartram’s Bass. From March to November of 2017 and 2018, individuals were collected from 160 sites across the upper Savannah River basin. Sites represented a gradient of key abiotic variables—watershed- and riparian-scale land use types, ecoregions, stream gradient, and elevation. Genetic analysis of 241 individuals from 50 sites revealed Bartram’s Bass were present at 33 sites, and hybrids were present at 21 sites. Conditional inference trees were used to predict the variables that drive Bartram’s Bass distribution. Forested land cover at the watershed scale was the most significant predictor of Bartram’s Bass presence (p=0.0236). Pure individuals preferred sites of greater than 75% forested cover (p<0.001). In less forested watersheds, there was higher probability of finding pure Bartram’s Bass at sites with greater watershed areas (p<0.001), and increased distance from reservoirs (p<0.001). Even when forested land cover was greater than 75% and stream gradients were low, sites closer to reservoirs were less likely to harbor pure fish (p<0.001). These results reflect the tradeoff between land cover and distribution for facilitating spread and hybridization of invasive fishes. iii DEDICATION I dedicate this thesis to the memory of my grandfather, Thomas Edward Judson, who passed away while I was completing this degree (3/19/1924- 2/11/2017). A farmer, hunter, angler, trapper, and lover of all things outdoors- I can only hope to live a life as full as his. I know this work would have made him proud. I also dedicate this to my mother and father, Karen Hansen and Doug Judson, for instilling in me a passion for hard work, and for the outdoors; I would not be where I am today had it not been for your love and constant encouragement over the years. iv ACKNOWLEDGMENTS Thank you foremost to my advisor Dr. Brandon Peoples for accepting me as one of your first Master’s students, and for providing me the opportunity to study an amazing species. This research has challenged me in ways I never thought possible, and allowed me to learn and grow in ways I didn’t know I needed to. I appreciate your patience and tactful support throughout the research and writing process. Thanks to my committee for their support and guidance, Dr. Troy Farmer and Mrs. Jean Leitner. Thank you to all who made this research possible, especially those who provided funding. I am forever grateful for the assistance of my field technicians: Jon Blalock, Alex Michaeli, Wesley Moore, and Luke Bell, as well as the many undergraduates who helped with lab work through Creative Inquiry courses. Thank you to my fellow graduate students, Sam Silknetter, Josh Vine, and Lauren Stoczynski for providing support and laughs through what might have otherwise been stressful times. Immense thanks also to Matt Walker, Tanya Darden, and Kimberly Kanapeckas from the South Carolina Department of Natural Resources (SCDNR) Hollings Marine Lab in Charleston, SC for processing all of my samples. The Clemson office of SCDNR also provided enormous field assistance which I am grateful for, and I would especially like to thank Mark Scott, Kevin Kubach, Drew Gelder, and Kenson Kanczuzewski for all the time and effort you put into my research. Finally, thank you to my siblings, parents, and grandparents- for shaping me into who I am, loving and supporting me, and inspiring me to pursue my passions relentlessly. v TABLE OF CONTENTS Page TITLE PAGE .................................................................................................................... i ABSTRACT ..................................................................................................................... ii DEDICATION ................................................................................................................ iv ACKNOWLEDGMENTS ............................................................................................... v LIST OF TABLES ......................................................................................................... vii LIST OF FIGURES ...................................................................................................... viii GENERAL INTRODUCTION ........................................................................................ 1 CHAPTERS I. NESTING MICROHABITAT CHARACTERISTICS OF BARTRAM’S BASS........................................................................................................ 6 Introduction .............................................................................................. 6 Methods.................................................................................................. 10 Results .................................................................................................... 13 Discussion .............................................................................................. 20 II. SPATIAL DISTRIBUTION OF BARTRAM’S BASS AND CONGENERS IN THE SAVANNAH RIVER BASIN ................................................. 25 Introduction ............................................................................................ 25 Methods.................................................................................................. 29 Results .................................................................................................... 34 Discussion .............................................................................................. 39 GENERAL CONCLUSION .......................................................................................... 47 APPENDICES ............................................................................................................... 51 Appendix A: Supplemental Tables .............................................................. 51 REFERENCES .............................................................................................................. 55 vi LIST OF TABLES Table Page 1.1 Table 1. Substrate categories and size ranges (mm) as derived from the Wentworth Scale (Wentworth 1922). .................................................... 12 1.2 Table 2. Linear regression model results for water velocity used at Bartram’s Bass nests and available in transects in the upper Savannah River in 2017 and 2018. ...............................................................................................